Critical Excitation Spectrum of Quantum Chain With A Local 3-Spin Coupling

TL;DR

This paper measures the low-energy excitation spectrum of a quantum spin chain with a local 3-spin interaction, confirming its universality class matches that of the 2D 3-state Potts model through conformal field theory predictions.

Contribution

It provides experimental verification of the conformal minimal model description of a quantum spin chain with three-spin interactions at criticality.

Findings

Excitation spectrum matches (D4, A4) conformal minimal model predictions.

Confirms the universality class with the 2D 3-state Potts model.

Validates the theoretical correspondence between lattice translations and conformal field theory.

Abstract

This article reports a measurement of the low-energy excitation spectrum along the critical line for a quantum spin chain having a local interaction between three Ising spins and longitudinal and transverse magnetic fields. The measured excitation spectrum agrees with that predicted by the (D$_4$, A$_4$) conformal minimal model under a nontrivial correspondence between translations at the critical line and discrete lattice translations. Under this correspondence, the measurements confirm a prediction that the critical line of this quantum spin chain and the critical point of the 2D 3-state Potts model are in the same universality class.